There is known a conventional construction machine including a lower travelling body and an upper slewing body slewably mounted on the lower travelling body, the upper slewing body having a slewing frame which bears an engine, a hydraulic pump, and an exhaust-gas after-treatment device. For example, Japanese Unexamined Patent Publication No. 2015-86573 discloses a construction machine including an after-treatment-device support cradle to support an exhaust-gas after-treatment device thereon while covering the hydraulic pump on the upper side thereof, the after-treatment device support cradle having a front leg, a rear leg, an auxiliary leg, and an after-treatment-device supporting. Each of the front leg and the rear leg of the after-treatment device support cradle has a bottom base extending in the lateral direction corresponding to the width of the after-treatment-device support cradle. The bottom base allows the after-treatment-device support cradle to support the exhaust-gas after-treatment device with respective substantially enlarged areas in which each of the front and rear legs is placed on the slewing frame.
However, in a certain size of construction machine, it is not easy to assure a space for disposing the after-treatment-device support cradle. For example, a large-sized construction machine provided with a center section and side decks provided on the opposite sides of the center section, thus having a large space in the periphery of an engine and a hydraulic pump, allows an after-treatment-device support cradle to be mounted on a slewing frame thereof even if the cradle includes a front leg or a rear leg with respective bottom bases each laterally extending. In contrast, for example, a construction machine including an upper slewing body whose rear portion rotates in a small range having a small slewing radius falling within a width of the lower traveling body, namely, a so-called tight quarter type of construction machine, has only a limited space in the periphery of the engine or the hydraulic pump, not allowing the above after-treatment-device support cradle having the above-described bottom bases each laterally extending to be directly mounted on a slewing frame thereof.